Many medical test procedures and packaging applications require containers capable of steam sterilization, are transparent and have good oxygen and moisture barrier properties. Often a single thermoplastic polymer is not able to provide all of these characteristics. For example, EVOH is a superior oxygen barrier, but cannot withstand steam sterilization conditions and has poor moisture barrier properties. Cyclic olefin copolymers (COCs) provide transpareny and good moisture barrier, but do not have good oxygen barrier properties, have only limited tolerance to steam sterilization, and have poor resistance to non-polar solvents. Amorphous polyamides such as Selar® PA amorphous nylon barrier resin and Trogamid® transparent polyamides provide good oxygen barrier or transparency, or both, but cannot withstand steam sterilization conditions. Similarly amorphous polymers such as polycarbonate and polystyrenes provide transparency, but lack oxygen barrier properties, and are prone to environmental stress cracking in contact with variety of chemicals.
One way to achieve desired combination of properties is to use a multi-layer structure wherein one layer material is selected to provide moisture barrier, another to provide O2 barrier and/or withstand steam sterilization conditions. However, these require complex manufacturing processes and increase the cost of the containers.
It would be desirable to have a single thermoplastic composition that provides an acceptable combination of oxygen barrier, moisture barrier properties and transparency and can withstand steam sterilization.
U.S. Pat. No. 5,213,860 discloses a plastic ampule comprising a tubular body made of a non-toxic chemically inert thermoplastic material.
U.S. Pat. No. 6,022,613, U.S. Pat. No. 6,407,182, U.S. Pat. No. 6,943,231, U.S. Pat. No. 7,133,209 and US Patent Publication 2011/0105697 disclose a variety of transparent molding compositions.